Nick/account registration and channel access

IRC never had registration as a core feature – nicknames and channels are transient, lasting only as long as they're used. Over time, however, people have started using various bots to manage channel access, and later network-wide services appeared to let people protect their nicknames and channels.

Almost all networks have services these days; however, they often differ in how the services work. All networks can be classified into several styles:

strict nickname ownership

On these networks, you register your nickname, and always identify while using the same nickname. Usually several nicknames can be "grouped" or "linked" to share settings (e.g. password) and privileges, but if you /nick to a different one, then you're automatically logged out. Accounts as a separate entity do not exist.

Such networks almost always offer nickname protection – if someone tries to use your nickname, but does not identify within 30 seconds, they will get renamed to a Guest or disconnected. Services also have commands to manually disconnect ("ghost").

(Often services set a +r user mode to mark you as identified, and the ircd shows "...is using a registered nick" in /whois.)

Examples: DALnet; networks that run IRC Services, Epona, Anope 1.8. The nickname registration service is almost universally called NickServ, along with the channel management service ChanServ.

no nickname ownership

On these networks, you register an account, usually based on your nickname but not tied to it in any way. You can also log into the account regardless of your current nickname, and this persists across /nick usage – the ircd remembers your current account separately and shows in your /whois.

Nickname protection is not available at all, although some services allow "ghosting" connections that are identified to the same account as you.

loose nickname ownership

This is very similar to the "no ownership" style, with a few minor exceptions.

On these networks, you register an account named after your current nickname. Channel access is given to the account, and you can log into it regardless of your current nickname.

However, such networks do offer optional nickname protection, and you can "group" several additional nicknames to the account.

Examples: freenode, staticbox; most networks that run Atheme or Anope 1.9.

no nick/account registration

Finally, in some networks, central registration is available at all. Channels often run their own bots to manage channel access; in other cases, channel ops just try to stay online 24/7 and re-op each other.

Some networks (e.g. EFnet) do have CHANFIX or a similar service to "fix" channels where all ops are lost; however, unlike ChanServ, CHANFIX uses an automated algorithm to determine who should regain op rights.